Fabricio José Pereira

Mecanismos anatômicos e fisiológicos de plantas de aguapé para a tolerância à contaminação por Arsênio

This work aimed to evaluate the anatomical and physiological characteristics of Eichhornia crassipes in response to arsenic stress. Plants of E. crassipes were grown in Hoagland hydroponic nutritive solution under greenhouse conditions at five arsenic levels: 0.0, 0.25, 0.50, 1.0 and 2.0 mg L-1 during 20 days. The plants showed an increase in photosynthetic rate, stomatal conductance, transpiration and Ci/Ca rate, as well as in the activity of all the enzymes in the antioxidant system, with higher activity in the leaves than in the roots, in all the treatments with arsenic. The anatomical characteristics observed on the leaves of the plants under higher arsenic levels showed an increase in stomatal density, stomatal index and spongy parenchyma thickness. Root anatomy showed no toxic evidences at any arsenic level; changes in the xylem and phloem characteristics were exhibited by the roots in the arsenic treatments, but no damage was caused to its structure and function. Thus, stress caused by arsenic intoxication at the levels tested, is not evident on E. crassipes plants, and the mechanisms of tolerance of E. crassipes are associated to anatomical and physiological changes.

Leaf anatomy and water potential in the coffee cultivars tolerance to water stress

Resumo - A cultura do cafe e de expressiva importância no mercado internacional, com uma producao anual de cerca de 120 milhoes de sacas beneficiadas e no Brasil, e responsavel pela geracao de mais de dez milhoes de empregos diretos e indiretos. O estresse hidrico e um fator ambiental que pode ser extremamente prejudicial para a cultura do cafe, sendo que a selecao de cultivares tolerantes e de grande importância, principalmente diante da expansao da cafeicultura brasileira para areas consideradas marginais para o cultivo do cafe por estarem sujeitos a deficiencia hidrica. Nesse trabalho foram avaliadas 15 cultivares de Coffea arabica quanto ao status hidrico e as caracteristicas da estrutura interna das folhas, verificando quais dessas cultivares sao potencialmente mais eficientes em tais condicoes. Dentre as cultivares estudadas destacam-se a Bourbon Amarelo e a Catimor como potencialmente mais eficientes em condicoes de estresse hidrico por possuirem: maior potencial hidrico, cuticula mais espessa, maior proporcao de parenquima palicadico, maior espessura da nervura central e maior densidade estomatica em relacao as demais variaveis. Dessa forma, as cultivares Bourbon Amarelo e Catimor sao potencialmente mais eficientes na reducao da transpiracao, fotossintese e translocacao de fotossintatos em condicoes de estresse hidrico, sendo mais indicadas ao plantio em regioes sujeitas a maiores deficits hidricos em relacao as demais cultivares estudadas. Palavra-chave - Coffea arabica. Plasticidade anatomica. Deficiencia hidrica.

Anatomia foliar de mandioca em função do potencial para tolerância à diferentes condições ambientais

Cassava is an important plant, cultivated in tropical regions, possessing great genetic variability which has still hardly been studied. The objective of this work was to examine the leaf anatomy of thirteen genotypes to assess their potential for adaptation in different environmental conditions. Fully unfolded leaves were collected from thirteen cassava genotypes being analyzed for quantitative changes in internal structure using optical microscopy. The experimental design was completely randomized with 12 replications and 13 treatments, the data were submitted to ANOVA and the Scott-Knott test. The different genotypes displayed great anatomical plasticity for most characters, with the most important changes occurring in the density and size of the stomata, tissue thickness of the abaxial epidermis, of the palisade and spongy parenchyma, in the phloem and xylem. The UFLA E, IAC 14 and UFLA J genotypes displayed as possibilities for xeric conditions, due to a high stomatal density, smaller stomata, a thicker adaxial epidermis, thicker palisade and spongy parenchyma, lower vulnerability of the xylem and greater thickness of the phloem, which would allow reduction in transpiration and better use of a large amount of incident radiation. The other genotypes exhibit more mesophytic features. Thus, cassava genotypes have anatomical plasticity, and can display the potential for selection of desirable characteristics for different environmental conditions.

Lead tolerance of water hyacinth (Eichhornia crassipes Mart. - Pontederiaceae) as defined by anatomical and physiological traits

This study aimed at verifying the lead tolerance of water hyacinth and at looking at consequent anatomical and physiological modifications. Water hyacinth plants were grown on nutrient solutions with five different lead concentrations: 0.00, 0.50, 1.00, 2.00 and 4.00 mg L-1 by 20 days. Photosynthesis, transpiration, stomatal conductance and the Ci/Ca rate were measured at the end of 15 days of experiment. At the end of the experiment, the anatomical modifications in the roots and leaves, and the activity of antioxidant system enzymes, were evaluated. Photosynthetic and Ci/Ca rates were both increased under all lead treatments. Leaf anatomy did not exhibit any evidence of toxicity effects, but showed modifications of the stomata and in the thickness of the palisade and spongy parenchyma in the presence of lead. Likewise, root anatomy did not exhibit any toxicity effects, but the xylem and phloem exhibited favorable modifications as well as increased apoplastic barriers. All antioxidant system enzymes exhibited increased activity in the leaves, and some modifications in roots, in the presence of lead. It is likely, therefore, that water hyacinth tolerance to lead is related to anatomical and physiological modifications such as increased photosynthesis and enhanced anatomical capacity for CO2 assimilation and water conductance.

Anatomy and physiology of Cattail as related to different population densities

The objective of this work was to evaluate the effects of the population density of Typha angustifolia plants in the anatomical and physiological characteristics. Plants were collected from populations of high density (over 50% of colonization capacity) and low density (less than 50% of colonization capacity) and cultivated under controlled greenhouse conditions. Plants from both populations were grown in plastic trays containing 4 L of nutritive solution for 60 days. At the end of this period, the relative growth rate, leaf area ratio, net assimilatory rate, root/shoot ratio, leaf anatomy, root anatomy, and catalase and ascorbate peroxidase activities were evaluated. Plants from high density populations showed increased growth rate and root/shoot ratio. Low density populations showed higher values of stomatal index and density in leaves, as well as increased palisade parenchyma thickness. Root epidermis and exodermis thickness as well as the aerenchyma proportion of high density populations were reduced, these plants also showed increased vascular cylinder proportion. Only catalase activity was modified between the high and low density populations, showing increased values in low density populations. Therefore, different Typha angustifolia plants show differences in its anatomy and physiology related to its origins on high and low density conditions. High density population plants shows increased growth capacity related to lower apoplastic barriers in root and this may be related to increased nutrient uptake capacity.

Anatomic and physiological modifications in seedlings of Coffea arabica cultivar Siriema under drought conditions

Due to the weather changes prognostic for the coming years, the understanding of water deficit and physiological responses of plants to drought becomes an important requirement in order to develop technologies such as mechanisms to assist plants to cope with longer drought periods, which will be essential to maintenance of Brazilian and worldwide production. This study aimed to evaluate ecophysiological and anatomical aspects as well as the nitrate reductase activity in Siriema coffee seedlings subjected to four treatments: Daily irrigated, non-irrigated, re-irrigated 24 hours and re-irrigated 48 hours after different stress periods. Non-irrigation promoted a reduction in leaf water potential being accented from the ninth day of evaluation onwards. Re-irrigation promoted a partial recovery of the plant water potential. Non-irrigated plants showed an increase in stomatal resistance and reduction of transpiration and nitrate reductase activity. In the roots, there was a decrease in nitrate reductase activity under water stress. Leaf anatomical modifications were significant only for the adaxial surface epidermis and palisade parenchyma thickness, this latter characteristic being higher in control plants. Stomatal density and polar and equatorial diameter ratios showed the highest values in plants under water stress. In the roots, differences only in the cortex thickness being bigger in the non-irrigated treatment could be observed. Therefore, Siriema coffee plants under water stress show physiological, biochemical and anatomical modifications that contribute to the tolerance of this genotype to these conditions.

MICROMORFOMETRIA FOLIAR DE Schinus molle L. (ANARCADIACEAE) EM DIFERENTES ALTURAS NA COPA

A caracterizacao foliar em arvores e essencial para a sua identificacao e utilizacao, bem como para se compreender as suas relacoes com o ambiente. Neste trabalho, objetivou-se o estudo da anatomia dos foliolos e das caracteristicas biometricas das folhas de S. molle em diferentes alturas na copa, em funcao das modificacoes ambientais e fisiologicas promovidas. As folhas foram coletadas em tres diferentes alturas na copa: base, meio e alto da copa em uma populacao cultivada de S. molle. Para as analises anatomicas, as folhas foram fixadas em FAA e armazenadas em etanol sendo, posteriormente, submetidas a seccoes paradermicas e transversais. As lâminas foram fotomicrografadas e as imagens analisadas no software UTHSCSA-Imagetool. Para as analises biometricas foram avaliadas a area, comprimento, largura, massa seca foliares, bem como a area foliar especifica. Os foliolos possuem epiderme unisseriada, estomatos anomociticos e ciclociticos, mesofilo isobilateral e camada subepidermica em ambas as faces da epiderme. Canais secretores e colenquima foram observados na nervura central e bordo dos foliolos. Ocorreram modificacoes nas espessuras da cuticula e do mesofilo, no sistema vascular, espessura do floema e na densidade estomatica de acordo com a altura em que os foliolos se encontram na copa das arvores. As folhas foram menores e demonstram reduzida area foliar para as partes mais altas da copa. A anatomia foliar de S. molle e diferente de outras especies do genero Schinus e demonstra modificacoes sob as diferentes condicoes ambientais e fisiologicas promovidas pelas diferentes alturas na copa.

Effect of potassium sources on the antioxidant activity of eggplant

Potassium participates in the essential processes in plant physiology, however, the effects of K sources on plant metabolism have been little studied. Also, in certain cases, K sources and concentrations may cause undesirable effects, e.g., soil salinization. The objective was to evaluate the effect of K sources and levels on the enzyme activity of the antioxidant system and protein content in eggplant (Solanum melongena L.) leaves and to determine the most suitable K sources for these physiological characteristics. The experiment was conducted in randomized blocks, in a 2 × 4 factorial design, consisting of two K sources (KCl and K2SO4) and rates (250, 500, 750, and 1000 kg ha-1 K2O), with four replications. The following variables were evaluated: plant height, number of leaves per plant, superoxide dismutase (SOD), catalase (CAT), and leaf protein content. There was an increase in CAT activity with increasing K levels until 30 days after transplanting (DAT), when K2SO4 was applied and until 60 DAT, when KCl was used; after this period, the enzyme activity decreased under both sources. The activity of SOD increased in the presence of KCl, but was reduced with the application of K2SO4. For both K sources, increasing rates reduced the protein content and number of leaves per plant, and this reduction was greater under KCl application. Thus it was concluded that KCl tends more strongly to salinize the soil than K2SO4. Both for KCl and for K2SO4, the increasing rates adversely affected the activities of CAT and SOD and the levels of leaf protein in eggplant. The potential of KCl to reduce the enzyme activity of SOD and CAT, leaf protein content and plant growth of eggplant was stronger than that of K2SO4.

Growth Curve and Development of the Internal Calli Structure of Eucalyptus camaldulensis Dehn

The objective of this work was to elucidate the growth curve of Eucalyptus camaldulensis Dehn. calli analyzing their anatomical modifications. A sigmoid aspect of the growth curve of the calli fresh matter was observed, with five different phases (lag, exponential, linear, deceleration and decline). In the lag phase, the highest growth percentage 87%, was observed, which reduced during the evaluation period to 17% in the linear phase. As for the anatomical analyses, cellular multiplications was observed during the lag and exponential phases and increase in cell size during the linear phase, promoting the calli volume growth and the establishment of the globular conformation.

Anatomical and physiological modifications in water hyacinth under cadmium contamination

The pollution of water bodies with heavy metals is generating increasing concern worldwide, and among those heavy metals, cadmium is one of the most toxic elements released into the environment. The present study aimed to evaluate the anatomical and physiological modifications adopted by the water hyacinth ( Eichhornia crassipes ) under cadmium contamination. The plants were grown in Hoagland solution in a greenhouse at five cadmium levels: 0.00, 3.5, 7.0, 14.0, and 28.0 μM. The net photosynthesis, stomatal conductance, transpiration rate, Ci/Ca ratio, antioxidant system enzymes activity, and anatomical traits in plant roots and leaves were evaluated. The plants exhibited increased photosynthesis, stomatal conductance, transpiration, and Ci/Ca ratios in all treatments containing cadmium. Antioxidant system enzymes displayed increased activity in the roots and leaves of plants treated with cadmium. Plants exhibited higher stomatal density and spongy parenchyma thickness under Cd contamination. The anatomical traits of the roots exhibited no evidence of toxicity or improved vascular system traits. Thus, Eichhornia crassipes demonstrated an ability to tolerate Cd by adopting changes in the anatomy, gas exchange and antioxidant system.